The field of the present invention relates to hand held or portable lighting devices, including flashlights and flashlight components.
Various hand held or portable lighting devices, including flashlight designs, are known in the art. Flashlights typically include one or more dry cell batteries having positive and negative electrodes. In certain designs, the batteries are arranged in series in a battery compartment of a barrel or housing that can be used to hold the flashlight. An electrical circuit is frequently established from a battery electrode through conductive means which are in electrical contact with an electrode of a lamp bulb. After passing through the lamp bulb, the electric circuit continues through a second electrode of the lamp bulb in electrical contact with conductive means, which in turn are in electrical contact with the other electrode of a battery. Incandescent lamp bulbs include a bulb filament. Typically, the circuit includes a switch to open or close the circuit. Actuation of the switch to close the electric circuit enables electricity to pass through the lamp bulb and though the filament, in the case of an incandescent lamp bulb, thereby generating light.
The light generated by a filament is typically reflected by a reflector to produce a beam of light. The filament typically includes a substantial point source of light which is the hottest portion of the filament and generates the most light. The position of the substantial point source of light of the filament relative to the reflector determines the type of beam that emanates from the flashlight.
The production of light from flashlights, which include headlamps, can be degraded by the quality of the reflector used and the optical characteristics of the lens interposed in the beam path. As a result, efforts at improving flashlights have often attempted to address the quality of the optical characteristics of the reflector or the lens. For example, more highly reflective, well-defined reflectors have been found to provide a better-defined focus thereby enhancing the quality of the light beam produced. Additionally, certain advances have been achieved with respect to the lens materials. Another significant factor in-the quality of light produced by a flashlight is the lamp bulb used in the flashlight. Several improvements have been made in the light emitting qualities of lamp bulbs.
Despite such efforts, there is still a need to improve the quality and intensity of the light produced by known hand held or portable lighting devices, including flashlights. The light pattern formed by the beam emanating from such light devices is frequently asymmetrical or elongated in shape which adversely impacts on the quality and intensity of the beam. These beam aberrations generally result from the fact that the flashlight lamp bulb is not properly aligned with the reflector of the assembled flashlight.
In various designs, the lamp bulb is supported within the lighting device by a holder or spacer within a battery compartment or barrel and extends into a reflector. Due to manufacturing and assembly operations and tolerances, however, after manufacture of the lighting device is fully completed, the lamp is typically misaligned with the reflector, resulting in degraded performance.
One attempt at addressing the misalignment of the lamp bulb is described in U.S. Pat. No. 5,260,858, by A. Maglica, which is hereby incorporated by reference. This patent describes a flashlight that includes a switch housing that partially floats within the barrel thereby helping to center the lamp bulb relative to the reflector. Although this patent's attempt to avoid a misalignment of the lamp bulb to the reflector is an improvement over the prior art, simply aligning the lamp bulb relative to the reflector does not ensure that aberrations in the projected light beam will be eliminated. This is because light is mostly emitted from the substantial point source of light of the lamp bulb. Accordingly, the critical component of the lamp that must be aligned relative to the reflector is the substantial point source of light of the lamp bulb.
An attempt at aligning the substantial point source of light of a lamp bulb to the reflector is described in the co-pending application Ser. No. 09/932,443, which is hereby incorporated by reference. This application describes a combination that includes a lamp base that secures a lamp bulb in such a way that the lamp bulb filament is aligned to a predetermined axis extending through the lamp base. The lamp base is then seated in a base receiver mounted adjacent to the reflector in a way that the predetermined axis of the lamp base is aligned to the axis of an axisymmetrical reflector. Although alignment of a lamp bulb filament to the reflector axis is significantly improved in this manner, alternate means to align the lamp bulb filament to the reflector axis are desirable.
Manually maneuvering the lamp bulb to address the misalignment problem is impractical. During operation, the temperature of an illuminating lamp bulb is too high to allow for manual adjustment. Also, the alignment of the substantial point source of light with the reflector is verified by assessing the quality of the light beam emanating from the light device. Accordingly, any attempt to maneuver the lamp bulb from the forward end of the light device will block the light beam and prevent the user from performing a contemporaneous visual assessment of the beam.
The present invention provides an apparatus and method for adjusting and maintaining alignment of the substantial point source of light with a characteristic feature of the reflector. The present invention further provides an apparatus and method for the user to perform a contemporaneous visual assessment of the light beam as the substantial point source of light adjustment is being performed.
Another feature of the present invention relates to the switch design. Switch designs that are adapted to close an electrical path between the lamp bulb and battery, or batteries, in response to axial movement of the head along the barrel and to open the electrical path in response to axial movement in the opposite direction along the barrel are known. While such switches have generally worked well for flashlights that employ smaller batteries of the AA or AAA type, known designs are less suitable for flashlights that employ larger battery sizes, such as C or D size batteries. One reason such designs are not well suited for flashlights employing larger batteries is that the positive electrode of the battery closest to the head end of the flashlight is urged against a conductor mounted flush against the bottom of the switch. As a result, the battery or batteries or the conductor may become damaged in the event that the flashlight is shaken or dropped. The problem also becomes more acute as the number of batteries connected in series increases due to the added weight, and hence momentum, of the multiple batteries.
One attempt at addressing the problem of damage that may occur to the battery or batteries due to physical impact to a flashlight is described in U.S. Pat. No. 5,804,331, by A. Maglica, which is hereby incorporated by reference. Although a protection to the battery electrodes is improved in the manner described in U.S. Pat. No. 5,804,331, alternate means to protect the batteries and other components of a portable lighting device, such as a flashlight, are desirable.
The development of lighting devices having a variable focus, which produces a beam of light having variable dispersion, has also been accomplished. In flashlights, the head assembly is typically rotatably connected to the barrel of the flashlight at the end where the bulb is retained. In addition, the head assembly is adapted to be controllably translatable along the barrel such that the relative positional relationship between the reflector and the lamp bulb may be varied, thereby varying the dispersion of the light beam emanating through the lens from the lamb bulb. While variable focus flashlights have also employed switches that are adapted to open and close in response to the axial movement of the head assembly, such flashlights have generally been limited to flashlights employing AA and AAA batteries for a variety of reasons, including some of those described above.